Some gear is so good it makes you feel inadequate.

Words and Images - James Raison

A knife fight broke out when the new C40s landed at La Velocita HQ. I won obviously because I’m skinny enough that the knives all bounced harmlessly off my rib cage. Plus I climb the most hills so I DESERVE these dammit.

THE WHEELS

The C40s are an all new design from Shimano, dropping into the gap from their previous C35 and C50 wheels. They’re not quite 40 mm deep, coming in at 37 mm but C37 doesn’t sound as cool as C40 so we’ll let that slide. The big news is the expanding external rim width that hits a plump 28 mm. The previous generation was 20.8 mm so that’s a substantial redesign. Most people will need to use the included low-profile Shimano pads made specifically to help the wheels squeeze between your calipers. They’re that wide.

The front wheel is rocking 18 straight pull spokes, and the rear has 21 cross-laced on the drive side and straight on the non-drive side. Nipples are sensibly external for easier servicing. Weight comes in at 770g for the rear, and 620g for the front. The rim profile has done some serious time in the wind tunnel with Shimano claiming they’re 2 watts over the 9000 series C50.

Hubs are a small evolution on the previous generation, but they have had an increase in flange spacing to bolster stiffness. They retain the same titanium freehub body, and thus keep their backwards compatibility with 10 speed drivetrains. The feel and sound of the hubs will be familiar to anyone whose used high-end Shimano wheels before. Very smooth, and very quiet.

I had some phat 28mm Vittoria Corsa Graphene tyres glued on and whacked them on the bike. Special mention, as always, has to go to the Shimano quick releases. They’re brilliant.

ON THE ROAD

The most surprising thing about the C40s is how unsurprising they are. The first time riding really high performance wheels is usually a theatrical experience full of pomp and circumstance. The Tune Airways I tested last year for example felt like sitting astride a nuclear bomb. I expected fireworks, rampaging elephants, Mad Max style fire-spitting guitars, and Keith Moon to smash a television over my head. The C40s? Nope. Nuthin but chill.

They spin up fast, as you’d expect, and hold that speed exceptionally well, as you’d expect. Their wide rims mated to thicc (yes, thicc) tyres gives them a damn smooth ride. My lightness means I run the tyres at around 65 psi, making for oodles of comfort and a buttery smooth ride, even on my ultra-firm Specialized Allez Sprint DSW. The hub is incredibly responsive too, immediately engaging and transferring your power to the drivetrain. No bouncing or clanging as the wheels try to to keep up with your accelerations.

My test rig was the stiff, and aggressive Specialized Allez Sprint DSW

Here’s the thing though, sink the boot in and they flippin fly. I don’t need superlatives here, they’re aimed at winning grand tours. They’re ridden by people named Froome, Porte, Dumoulin, and stacks of others. Safe to say they’re total overkill for me.

So what can you racers expect from them? I lent this set to a mate who spent some time getting to know them, including pancake flat crit - far from their ideal hilly terrain. His prognosis: “a religious experience.” This is a guy who already races on some significantly lighter hand-built tubs.

Flogging through the hills is intoxicating. The wheels climb, descend, and roll… well… like grand tour stage winners. Ask for speed and you shall receive. They hit every target; stiff, light, aero, comfortable, and incredibly stable. I absolutely love riding them.

HITTING THE SKIDS

Perhaps the most interesting aspect of the C40s is the stopping. Braking is a tale of great power but low feedback. I’m not kidding when I say they feel closer to discs than my aluminium clinchers. There’s a lot of power but not a lot of feel.

You need a wide reach to get around these rims

I’m using Shimano’s new and ultra stiff R8000 calipers added to those low profile pads and that combo initially caused some accidental skids when coming to a stop at intersections or traffic lights. I found it difficult to gauge how hard I was braking. Like most carbon, these wheels like bursts of power rather than a more gentle lead-in that you can get away with from aluminium. There was a distinctive audio feedback with the C40s that It starts with a whoosh, amplifies to whistle, then it has a slight judder, and the final criscendo is that oh-so-carbon squeal. Those sounds became my reference point for how hard I was on the anchors.

I didn’t detect any fade with higher heats but that could be due to winter/spring testing when temperatures haven’t been very high. I take carbon wheels on the same braking-heavy, tight, and twisty descent to test their heat dissipation. All carbon clinchers have faded on that stretch of road. The C40 tubs didn’t.

Now, the elephant in the room: rain. I didn't ride these in significant rain in my 800km test period. I tried, too! Either the rain never eventuated or it was insubstantial. So, I don't know how they go when it's hosing down.

A SWANSONG?

A thought occured while riding on the C40s; this could genuinely be the last generation of rim brake tubulars from Shimano. Discs will dominated sooner than later so Shimano have to be asking themselves if revamping this generation of C40 and C60 is economically viable in their 3-4 year groupset cycle. They’ve already showcased the C40 disc variants that will grace the pro peloton in 2018.

If this is the rim brake tubular swansong, it’s a very good one.

WRAPPING UP

What you get with the C40s is speed aplenty, smoothness aplenty, stability aplenty with sensible design... aplenty. Nothing on the spec sheet jumps out as impressive or insane. They go like stink and stop very well once you're used to it. Dare I say these are sensible race wheels? I do. They are. I love every kilometre I ride on these wheels.

Disclosure statement: These wheels were sent for review by Shimano Australia. It is not a paid review.